EVLOS for Drone Operators in the UK

What is EVLOS?

EVLOS stands for Extended Visual Line of Sight and involves operations where the pilot visually follows the UAS using technology, while the aircraft remains within the visual line of sight. This means the pilot can see the UAS and respond to potential threats and hazards in the airspace.

According to the UK Civil Aviation Authority (CAA), EVLOS is an operation where the pilot in command (PIC) maintains continuous situational awareness of the airspace through visual observation, possibly supported by technological means. The PIC has direct control over the UAS at all times.

• EVLOS is an extension of VLOS through support with technology, such as screens, drone spotters, or other visual aids.
• The pilot must be able to intervene and safely control the UAS based on continuous visual observation.
• It is not a BVLOS operation, as the aircraft remains visually observable within the airspace.

Difference Between VLOS, EVLOS, and BVLOS

It is important to understand the difference between VLOS, EVLOS, and BVLOS, as this affects the required operational procedures, permissions, and risk assessments.

VLOS (Visual Line of Sight) means the pilot sees and follows the UAS directly, without aids. EVLOS involves the pilot using supporting technology but maintaining a direct visual link with the aircraft. BVLOS (Beyond Visual Line of Sight) operations occur outside the pilot's direct sight and require extensive safety measures and authorisation.

• VLOS: pilot sees the UAS directly, without aids.
• EVLOS: pilot sees the UAS with technical support but within the visual field.
• BVLOS: pilot does not see the UAS and must rely on other techniques and approvals.

EVLOS within the UK Regulatory Framework

EVLOS operations fall under the Specific Category within the UK regulatory framework, meaning an Operational Risk Assessment (such as UK SORA) must be conducted, or a suitable PDRA or Standard Scenario (STS) can be applied.

Since EVLOS sits between VLOS and BVLOS, UAS operators often utilise standardised scenarios or a PDRA tailored for EVLOS operations, provided the relevant requirements are met.

The UK Civil Aviation Authority (CAA) is the competent authority responsible for approvals and oversight of EVLOS operations. An operational manual (Concept of Operations and Emergency Response Plan) must be well-prepared, clearly explaining how visibility and safety are ensured and how risks are managed.

• EVLOS requires a UK SORA or application of a UK PDRA/STS.
• CAA manages licensing and supervision for EVLOS in the UK.
• A ConOps must clearly document how continuous visual awareness and safety measures are maintained.

Practical Considerations for Drone Operators

Practically, EVLOS means effectively using technical aids to maintain visual contact with the UAS, such as a co-pilot or visual observer communicating with the pilot in command.

Procedures must ensure the airspace remains clear of conflicts and allow rapid intervention if unexpected situations arise.

Common pitfalls include inadequate visual coverage, poor communication between the pilot and observers, and incomplete operational manuals.

• Utilise drone spotters or additional visual observers when possible.
• Ensure communication paths are clear, timely and effective between all team members.
• Keep operational limits and risk mitigation measures thoroughly documented.
• Always verify compliance with current UK CAA regulations.
• Prepare your documentation, including ERP and General Risk Controls (GRC), carefully for potential CAA inspections.